A quick documentary of my FPV flight to Robben Island, where Mr Nelson Mandela was imprisoned for 18 years.
Back then I was very worried about flying over water...
This was before Cruize mode :)
About 16km and 35 minutes, safe touch down!
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brilliant stuff!!!!!
The key is the smaller battery will never deplete. It will maintain the same voltage as the rest of the system, just contribute to the power delivery. As long as it can maintain the discharge rate.
I've done quite a bit of research asking experts at rcgroups and it makes sense and works perfectly in practice.
The reason for the specific combination is I estimated I need as much mah with safety margin. I didn't need 10ah.
Hein,
What prevents the discharge from lower capacity batt when it is depleted while the bigger capacity batt still has charge? And how do you manage to keep the voltage same in both Batt? When time is constant as load is constant accross both batt then one( smaller capacity) batt has to deplete earlier than the other. This is when they are connected in parallel. When different size batt with same volt type are connected in series, it is different story.
At this point the lower capacity batt should either become a load to bigger capacity batt or it will discharge below its safe level, either of the one should happen is what my minimal brain tells me.
I imagine your setup as different size wheels fixed in a car ( parallel side). They will work but there will be drag towards small wheel side and after some time you will find uneven wear/tear on the wheels. IMHO , I feel Nat and Mathew are right.
In any case why do want to use different size batt instead of same? Is it because that is what you have or any other reason? :)
cheers
Morli
Matthew is correct, although unmatched battery configurations will work to a point you do run the risk of damaging the lower capacity pack if you draw more than twice the lesser packs capacity. Think about it, why do you only see packs made up of individually matched cells? In the case of a normal 3S LiPo you have 3 3.7v cells, if they weren't matched say 2200mAh each but instead 2200,2200,1800 then when you consumed more than 1800mAh you would see a dramatic drop in voltage and possibly ruin the cell.
Your unmatched parallel configuration will work as long as the actual current demand on each pack is equal and you don't exceed twice the capacity of the smaller pack. As a side note C ratings will play a role here as well, if you have two packs with different capacities, but the same C rating, you will draw more current from the pack with the greater capacity than the one with the smaller capacity. Finally if the current demand exceeds the C rating of the smaller capacity pack you will see swelling and possible damage to the smaller capacity pack, while the larger capacity pack will remained unharmed.
The short answer is you may get away with it for a while, but eventually the smaller capacity pack will either begin to show signs of reduced performance or will be permanently damaged.
Regards,
Nathaniel ~KD2DEY
I agree with Hein, I think it's... a strange thing to do, but technically it should work.
Dont use two different capacities in parallel... by adding a 2200mAh to a 5000mah pack your not creating a 7200mah pack your actually creating a 4400mAh pack since it will discharge equally from both packs (in theory), and once you hit 4400mAh discharged your 2200mAh will start to over discharge... it will damage it pretty quickly. If your going to parallel up packs, which i do also, they need to be pretty close if not the same capacity to make it worth wile and safe for your packs.
Whale/shark spotting , another good application for tourist industry , marine biologists :)
Another awesome video. Hmm Imagine Seal Island in False Bay (Great white shark hangout)
Here in the Garden Route Mossel Bay area - local seal island is 500m offshore from Diaz beach
another favorite Great White Shark hangout
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